Oil burner



SePf- 24, 1957 R. R. WITHERELL 2,807,319

on. BURNER Filed Sept. 25, 1952 2 Sheets-Sheet 1 Sept. 24, 1957 R. R. wlTHERELL OIL BURNER 2 Sheets-Sheet 2 Filed Sept. 23, 1952 .NNN NNN NNN f NN NNN WWN NNN .NNN

United States Patl 2,807,319' j on. BURNER Application September 23, 1952, 'Serial `No.^31il,961 6 claims. (el. 15a-36m This invention relates to oil burners and has particular reference to'oil burners of the lowV pressure type wherein oil "and air at relatively low pressures are mixed Vin a nozzle andv discharged Iin the form of Aa spray of air and nely divided oilparticles into a stream of secondary air soasto -provide a combustible mixture.

This invention has reference to certain new and useful improvements in voil burners of this type which simplify the construction and reduce the cost of manufacturing. The invention also makes it possible tojbuild burners of this type of relatively small capacity, and in additton provides certain inherent advantages in connection with the installation and use of the burner. A

The structure as herein disclosed and 'claimed Vconstitutes an improvement upon lthat disclosed and claimed in my prior copending application Serial No. 234,084, led June 28, 1951, now Patent Number 2,724,433, and the present application is a continuation-in-part of my prior copending application Serial No. 240,629, led October 7, 1,951, and now abandoned.

A principal object of the invention, therefore, is to provide a novelA and simplified construction for oil burners of the low pressure type with particular reference to oil burners adapted for domestic use.

Another object of the invention is to provide an oil burner which is ecient and dependable in operation and yet relatively inexpensive to manufacture.

' yOther and further objects of the invention will be apparent from'the following-description and claims and may be understood 'by reference to the accompanying drawings, of which there are two sheets, which by way of illustration show preferred embodiments of the invention and -what I now consider to be the best mode in which I have'contemplated applying the principles of my invention. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.

In the drawings:

Fig. 1 is a vertical sectional view of an oil burner embodying the invention, certain parts being illustrated schematically;

Fig, 2 is a fragmentary sectional view showing a modiiied form of regulating means for adjusting and controlling the air pressure in the reservoir;

Fig. 3 is an enlarged sectional view of the oil and air mixing nozzle;

Fig'. 4 is an elevational view of one end of the inner part of the oil and air mixing nozzle showing the slots which conduct the oil and air mixture to the tip chamber of the nozzle; and

Fig. 5 is a vertical sectional schematic view illustrating amodiiied vform of the invention.

As illustrated in the embodiment of the invention selected for purposes of illustration, an oil burner according to my invention comprises in general a reservoir vfor containing a body of oil and air under pressure, an electric motor 12, a secondary air blower indicated generally at 14 anddriven -by the motor 12an air pump 2,8013 19 Patented Sept, 24, 1957 t lz 16 ofthe positive displacement type, an koil and air mixing nozzle 18, and a draft pipe 20 in the end of which the nozzle .18'is arranged, vthe draft pipe serving to direct a stream of secondary air past the nozzle l18 and the nozzle serving to mix the oil and air supplied thereto and to discharge such mixture of oil andair in the form of a spray of air and finely divided oil particles. Spaced electrodes, one of which is indicated at 2,2, are arranged adjacent the nozzle, and form apart of a conventional ignition system, and are adapted to ignite the combustible mixture formed by the 'secondary air and the spray discharged from the nozzle 18. Thecombustible mixture so formed will have a shape generallylik'e that of a cone and 'will burn just outside of the discharge end 24 of 'the draft pipe 20. t

The nozzle 18, as `illustrated in Figs. 3 and 4, consists of an inner part 26 disposed within an outer part or casing 28. The inner part, as illustrated, is formed to provide a series of rair conducting slots or passages 30 through which primary air tl'ows to 'the annular mixing chamber 32. Each ofthe slots 30 is provided with an oil port 34 which discharges'a jet'of oil under pressure into the' air flowing through the slots 30 for mixture therewith, and such mixture flows into the annular chamber 32 which is formed by a reduced end 36 of the part 26 and a surrounding part of the casing 28. From the chamber 32 the oil and air mixturevilows through a series of slots 38 into the tip chamber 40, the slots 38 delivering the mixture into the chamber 40 in such a way as to cause the mixture to rotate in said chamber about the longitudinal axis of the nozzle.

The tip chamber is provided with a sharp edged, circular orifice 42 through which the mixture is discharged in the form of a conicalY spray of air and finely divided oil particles, the mixture breaking over the sharp edge of the orifice 42'as it is discharged from the chamber 40. A conical projection 44 extending from the reduced portion 36 of the part 26 projects toward the oriiice 42 and cooperates with the wall of the casing k28 in which the orifice 42 is formed to define an annular tip chamber conical in form. i

The slots 30 form air passages and the oil ports 34 form oil passages, and-such passages intersect or converge so as to effect amixing of the oil and air in the nozzle. Oil and primary air are delivered to such oil and air passages Yof the nozzle preferably at substantially the same pressure, say, for example, at a pressure of the order of two to live pounds per square inch. An oil pipe 46 at one end ythereof communicates with an axial duct 48 in the part 26, which in turn communicates with thefinn'erl ends of the passages 34 so as to supply the same with oil.

The other endV of the pipe 46 communicates with a duct 50 formed in acasting or frame 52, and a duct 54 com`V municates at its upper end with Vthe duct 50 and at its lower end with a pipe 56, the lower end of the pipe 56 terminating adjacent the bottom of the reservoir 10 below the level of the oil therein so that oil will llow underthe pressure in the reservoir 10 through the pipe V56,` the ducts 54 andv50, the pipe 46, and the duct 48 to they oil yports or passages 34 of the nozzle.

In order to meter the flow-of oil from the reservoir 10- to the nozzle 18 a metering orice 58 may, `as illustrated, be arranged between the duct 50 and the end -of the pipe,- 46, or the cross section and the length of the passages 34 and/ or 48 may be so dimensioned as to meter. the flow ofoil which is discharged Ifrom the passages 34 into the air passages 30 and so that the ow of air through the air,`Y

passages or s-lots 30 will have an aspirating effect on the. oil ports 34. Since the pressure at which oil is supplied 3 comparedwith the size of the metering orifices used in the nozzles of high pressure oil burners.

The casing 28 of the nozzle may, as illustrated, be mounted uponone end of an air conducting pipe 60 which supplies air to the slots 30, the other end of the pipe 60 being connected to an L-shaped duct 62 in the casting 52 and the oil'pipe 46 extending through the air pipe 60. The duct 62 communicates with the upper end of the reservoir 10, and 4with the pipe 60 serves to conduct air under pressure from the reservoir to the air passages of the nozzle.

The reservoir 10 may, as illustrated, be formed by a cup-shaped container, the top of which is closed by the casting or frame 52 on which the motor 12 is mounted. The casting 52 is formed to provide bearings 64 and 66 for the armature shaft 68 of the motor 12. The field 70 ofthe motor 12 is mounted on the sleeve 72, which in turn is mounted upon casting 52. The shaft 68 projects above the motor 12 into the fan chamber 74 where it has aixed thereto a centrifugal type of fan wheel 76. A `casing 78 encloses the upper part of the reservoir 10 and is provided with a cap 80 which enc-loses the motor 12 and `defines the fan chamber 74 and also an inlet 82 therefor. The draft pipe is secured to and projects from the casing 78, and between the sleeve 72 and the cap 80 there are formed air passages 84 which conduct air discharged by the fan wheel 76 around the motor and thence through the casing 78 to the draft pipe 20.

The shaft 68 projects below the frame 52 and has airixed thereto for rotation therewith the rotor 86 of the air pump 16. The positive displacement air pump 16 of the rotary sliding vane type is adapted to compress air and discharge the same under pressure through the outlet 88. A port 90 in the casting 52 serves as an inlet `for the air pump 16, the port 90 opening upwardly into a cavity -92 which surrounds the bearings 64 and 66.

A perforate plate 94 extends across the top of the cavity 92 and an oil collecting ring 96 projects upwardly from the outer wall of the cavity to a point above the lower end of an oil slinger 98 carried by the shaft 68 just below the armature 100. A duct 102 communicating at one end with the duct 50 communicates at its other end with an oil chamber 104 located between the bearings 64 and 66 so that oil may be supplied to such bearings. Oil which escapes upwardly from the upper bearing 64 is discharged yby the oil slinger 98 against the collector ring 96 and drains downwardly through` the perforate plate 94 to the inlet 90 of the pump 16, and is carried by the air which enters the pump through the pump for lubricating the same and then discharged through the outlet 88 thereof. Oil also ows downwardly beyond the 4lower bearing 66 along the shaft 68 to -lubricate and seal the rotor 86 of the pump with respect to the end plates thereof and the sliding vanes carried by the rotor 86.

Aii under pressure from the outlet 88` of the pump 16 is conducted by a pipe 106 :to the venturi 110 of an injector 108 so as to energize or actuate the same, the injector 108 discharging into the reservoir 10 above the oil level therein. The pressure `at which air is supplied from the pump 16 to the venturi 110 of the injector 108 is approximately seven to nine pounds per square inch. The pump may be provided with a conventional pressure regulating adjustment (not shown) whereby the discharge pressure thereof may be regulated. As previously indicated, air under pressure from the reservoir is conducted by the duct 62 and the pipe 60 to the air passageways 30 of the nozzle, and air is always vfree to flow to the air passages 30, This arrangement will be effective to purge the nozzle 18 of oil at the end of each operating cycle. l v

The maximum pressure of air in the reservoir 10 may be controlled by a weight valve 112 which is adapted to be seated on a seatat the end `of a duct 114 which com.- municates with the duct 62. In lieu of the weight valve 112, which is nonadjustable but which of course might be replaced -by a valve of different mass, the arrangement illustrated in Fig. 2 may be employed. In Fig. 2 like reference characters have been employed to indicate parts which are the same as those shown in Fig. 1.

As shown in Fig. 2, a passage 116 intersects the duct 62. and communicates at its end with the cavity 92. One end of the passage 116 is reduced to form a valve seat 118 for cooperation with a needle valve 120 which is threadedly mounted in a bushing 122 disposed in the passage 116. The end of the valve is slotted for receiving a screw driver so that the valve member 120 may be advanced or retracted with respect to the seat 118 so as to vary the extent of opening between the seat 118 and the valve member 120, and the extent of this opening will regulate the amount of air which is bled out of the reservoir 10, thereby to control the maximum pressure thereof. Access to the valve member 120 may be had by removal of the threaded plug 124. This valve arrangement functions like that shown in Fig. l to control the maximum pressure in the reservoir 10, but differs from Fig. 1 in that it provides a convenient means by which such pressure may be varied. Since the: volume of oil delivered to the nozzle 18 is dependent upon the air pressure within the reservoir 10, the adjustable valve arrangement of Fig.`

2 provides a means of adjusting the combustion rate of the burner.

An oil supply line 126 communicating at one end with an oil storage tank and at its other end with a duct 128 in the casting 52 is arranged to supply oil to the reservoir 10, and means are provided, as will be presently described, for imposing the suction at the throat of the venturi 110 on the interior of the line 126 for causing the iiow of oil therethrough into the reservoir 10.

A vessel 139 disposed within the reservoir 10 has its interior connected by `a pipe 132 with the duct 128. A duct 134 provides communication between the interior of the vessel at the upper end thereof and the throat of the venturi 110 so as to create a negative pressure within the vessel 1,30 during operation of the injector 108. This pressure or suction is effective to cause flow of oil through the line 4126 and the duct 128 into the vessel 130. A normally closed shutoff valve indicated generally at 136 arranged in the oil supply line 126 is maintained open by the reduced pressure within the vessel 130, as will be described more fully hereinafter.

When the level of oil in the vessel 130 attains a predetermined maximum, an air valve or vent indicated generally at 138 is opened by a snap acting mechanism so as to equalize theA pressure between the reservoir 10 and the vessel 130. Oil will then flow from the vessel 130 through the duct 140 and past the check valve 142 into the bottom of the reservoir 10 until the level of oil in the vessel 130 is the same as the level of oil in the reservoir 10. At this time the oat-actuated snap acting mechanism will close the air vent 138, whereupon the injector 108 will be effective again to reduce the pressure within the vessel 130 and cause the flow of oil into the vessel.

The vessel 130 and its associated mechanism function as a transfer mechanism for imposing the suctionfproduced at the throat of the venturi 110 on the oil line 126 and for delivering the oil which ows through the pipe 132 into the reservoir 10 without flowing through the injector 108. At the time that the valve 133 is open, the valve 136 is closed so as ,to prevent pressure in the reservoir 10 from being dissipated through the pipe 126. Thus the delivery of oil to the reservoir 10 will not interfere with the supplying of oil and aii` under pressure to the nozzle 18 or with the firing of the burner.

The air vent or valve 138 includes a movable valve member 144 carried on a stem 146 which projects through an opening 148 formed in a bushing 150, the upper end of the bushing forming a seat for the valve member 144. The lower end of the stern 146 engages a lever 152 pivoted on the member 154- and a spring 158 is connected to the remote ends of the levers 152 and 156. The free end of the lever 156 extends into a groove ina-collar 160 mounted on one end of a sleeve-162 which is slidable upon a pin 164 secured in the upperwall of the vessel130. A oat 166is carried 4by thesleeve 162, and when the oil level Yin vthe vessel 130 rises,=thecollarr1,60 will 4move the lever 156 in a clockwisedirectionabout its -pivot'on the member 154, --and after the spring 158passes dead center it will zpivot the lever 152 in a counterclockwise direction so as to move the stem 146suticiently tovunseat the valve member 144vfrom its seat, thereby to open the communication- 148 ybetween Vthe reservoir 1t) and the interior of the vessel k130. Thiswilhaspreviously described, permit the equalization of pressureszin the vessel 130'and in the reservoir land'permit the -ilow of oil from thev vessel 130 through-the d uct 140 andgpast the check valve 142 into :the lowerV end of .the reservoir 310. When thel level of oil in the vessel 13G 'falls,'=oat' 166 will fall, and through the snap acting mechanism just describedreturn the levers 152 andV 156 to the position as illustrated, thereby permitting the valve member 144' to seat.

The valve 136 comprises a casing 170 which forms a duct 172 'and a duct 174, such ducts forming a part of the oil line 1726. A Vvalve seat 176 is yformed around one end of a bore 178 which communicates with one end of the-duct -1-72. Atmovable valve member A180 mounted on a stem182 is adapted fto seat on ythe seat 176 so as to close the valve 136, a spring 184 reacting on the valve member 180 and biasing the same toward its seat 176. The valve member 180 is disposed in la chamber 186 which communicates with one endof thenduct 174 so that when the valve member 180 is unseated communication will be established between ducts l174 and 172 and oil will ow through the line 126 under the inliuence of suction in the `vessel 130.

The stem 182 is slidable in the bore 178 and at its lower end engages a diaphragm 190 arranged in a chamber r192. One face ofthe diaphragm 190 is exposed to the pressure in the duct 172 through the duct 194, while the opposite vface is exposed to atmospheric pressure through the duct 196. Thus, :the suction or negative pressure in the vessel l130 communicated to 'the upper face of the diaphragm 190 through the duct 194'will cause the diaphragm 4190 to ymove upwardly 'and' therei by lift the stem 182 and unseat the valve 180, permitting oil to flow from the chamber 18,6 through the bore 178 into theduct 172l and through the oil line 126 into the vessel 130. As soon as the valve 138 opens, the suotion or negative pressure in the line 126 V-will disappear, whereupon the 'spring 184 will seatthe valve 180 and maintain it seated until the valve 138 closes, thereby preventing dissipation of the pressure in the reservoir through the line 126 when the valve 138 is open. The stem 182 is provided with a reduced portion which permits the How of oil'through the bore 178 when the valve 180 is unseated.

In addition to the ignition system previously referred to, any conventional or desired control arrangement may be associated with the oil `burner for controlling the `operation thereof in response tothe demands for heat. Since the pressure in the reservoir 10 will be dissipated at the end of each 'cycle'of burner operation, it will'be apparent that at the start of each cycle of burner operation sufficient pressure will have to accumulate within the reservoir 1t) before any oil will flow to the burner nozzle, since the flowof oil to the burner nozzle is in response tothe pressure in the reservoir 10. The system preferably is so designed that no oil will flow to the nozzle until after primary air at the desired pressure is being supplied to the nozzle 18 andsecondary air is also being supplied through the kdraft pipe 20 past the nozzle 18. Thus, as soon as oil flows to the nozzle 18 there will be sufficient primary and secondary air available to form a combustible mixture, "and in .addition at the end of each cycle of burner operation the flow of primary and sec- Ondary air will continue after the oil supply to the nozzle through the conduit 218 tothe venturi of the injector 220.

During the operation of the air pump 216 the injector 220 functions to create within the transfer vessel 222 a negative pressure, as the throat of the venturi of the injector 220 =is connected through conduit 224 and through the iioat controlled valve 226 with the interior of the vessel 222, with the parts arranged as illustrated.

. One end of an oil supply line 228 communicates with the interior of the transfer vessel 222, and in the oil supply line 228 between the vessel `222 and the fuel supply' there is arranged ya normally closed, pressure responsive valve 236 which is ofthe same construction as the valve 136 and which operates `in 'the same way. Thetransfer' vessel 222 is arranged within the oil and air reservoir 238, the top of which is closed by the casting to which the motor 212 andthe air lpump 216 are assembled. An oil line 240 has one end projecting into the body of oil in the bottom of the reservoir 238 while the other end extends to the nozzle 242 ,and communicates with the oil passages thereof. The nozzle 242 is diagrammatically illustrated in Fig. 5 and may be of exactly the same construction as disclosed in Figs. 3 and 4.

In the upper Vpart of the reservoir an air line 244 supplies `air under pressure from the reservoir 238 to the air passages of the Ynozzle 242 for mixture with the oil supplied thereto', the nozzle. being adapted to mix the oil and air and discharge the same as a primary mixture into a-stream of secondary air which flows through the air tube 246 and over the nozzle, the secondary air mixing lwith vthe primary mixture to form a combustible mixture which burns -justoff the vdischarge end 0f the air tube. As in the case of Fig. l, the secondary air may be supplied `by arotary type fan 248 driven by the motor 212. The injector` 224) ldischarges, into the reservoir 238'so as to accumulate therein-a mass of air under pressure above and in `contact with the voil therein.

. The-fuel oil within the reservoir 238 is caused to flow through-theoil line 240 to thefoil passages of the nozzle 242 .and-,from such oil passages into the passages in the nozzle wherein the oil and air are mixed, due to the pressure diierential created in the passageways 30 (Fig. 3) of the nozzle by the Yiiow of air through such passageways 30 which are positioned at right angles to the extremities of the oil ports 34. The oil and air mixture then .ows into lthe mixing chamber 32 and through the slots 38 into the swirl chamber, from whence` it is discharged into the secondary air stream in the form of a spray of air and finely divided oil particles.

The transfer vessel 222 has associ-ated with it a nor-y mally closed', pressure equalizing valve indicated generally at 250 andra normally closed vflow control valveindicated generally at 252. When the float 254 for the float controlled valve 226 is in its lower position as shown,

the valves 250 and 252 are closed so that the vacuum created by the venturiof the injector 220 is effective to exhaust the transfer lvessel 222 and reduce the pressure therein, which will r"open the valve 236 and cause oil from the fuel supply to ow into the vessel 222. VAs the liquid level rises within the Vessel 222 the buoyancyof the oat 254 causes it to move upwardly on the stem 256 until the top of the 'float 254 contacts the head 258 Von the stem, whereupon the head 258 will moveupwardly with the float until the valve seat260 carried by the head 258 contacts and' seats on the valve seat 262 of the valve 226, thus closing the valve 226 and shutting off the communication between the interior of the vessel 222 and the throat ofthe injector 220. Theclosing of the valve 226 The spring 268 which biases the valve 252 toward its closed position is heavier than the spring 270 which biases the valve 250 toward its closed position so that the vacuum applied to the valves 250 and 252 will be effective to open the valve 250 before opening of the valve 252. When the valve 250 opens the diaphragm 264 will move the valve member carried thereby away from its valve seat, thereby porting the top of the vessel 222 to the interior of the reservoir 238 through the valve 250 which permits equalization of the pressures within the vessel 222 and the reservoir 238. Thereafter the suction applied to the valve 252 will be effective on the diaphragm 266 thereof to move the valve member carried thereby away from its seat, thereby permitting oil from the vessel 222 to flow through the ports 272 `and 274 in the valve 252 into the reservoir 238 under the influence of gravity and until the level of the oil within the vessel 222 is equalized with the level of oil within the reservoir 238. The equalizing of the pressures between the vessel 222 and the reservoir 238 causes the vacuum effective on the diaphragm of the shutoff valve 236 to be dissipated, thereby permitting the valve `to close. The flow of oil from the vessel 222 into the reservoir 238 allows the float to fall to a lower position where it contacts the lower enlarged end 276 of the stem 256. As the weight of the float becomes effective on the stem 256, the valve seat 26) is moved away from its seat 262 thereby porting the inside of the vessel 222 to vacuum. This reduces the vacuum exerted on the diaphragms 264 and 266 of the valves 250 and 252, thereby permitting the springs of these valves to close the same, whereupon the total negative pressure created by the injector 220 is again applied to the interior of the vessel 222 thereby reestablishing the fuel pumping cycle.

The air pressure developed within the reservoir 238 `is controlled by the resistance imposed by the nozzle 242 in conjunction with a spring loaded diaphragm type pressure regulator indicated generally at 280. In lieu of or in addition to the resistance to ow created by the nozzle, the air and oil lines 240 and 244 to the nozzle 242 may have pressure regulating means associated therewith if desired, although with the arrangement as illustrated in Fig. such are not necessary.` The pressure regulator 280 is adjustable and of a sensitive type, being instantaneously responsive to a change in pressure occurring in the reservoir 238 at the instant of opening of the pressure equalizing valve 250 and subsequent equalizing of the ,pressure within :the vessel 222.

The air bypassed by the regulator 280 flows through the duct 281. to the intake passageway 282 for the air pump 216. The diaphragm 284 of the regulator 280 is exposedV to the pressure withinlthe reservoir 238 and the design of the regulator is such that the pressure within the reservoir 238 is maintained with a minimum reduction r(approximately two to four ounces) at the beginning of each transfer cycle to minimize fluctuations in combustion at such time. The pressure regulator being adjustable by means of the screw 286 provides a means for adjusting the combustion rate of the burner as the volume of oil delivered Iby the aspirating type nozzle 242 is dependent upon the air pressure within the reservoir 238.

A conduit 290 is arranged so as to extend from a point below'the surface of the oil within the reservoir 238 to a cavity 292 surrounding the motor shaft 294 to supply fuel oil to the bearings for lubrication, the oil flowing through the conduit 29) `as a result of the air pressure in the reservoir 238. The oil for lubrication flows to the upper and lower bearings of the shaft 294 and that discharged `by the upper` hearing is discharged by the oil slinger 296 into the space 298 from which it flows into the air `intake 282 for the pump, The oil passing through the lower bearing [lows through the circular relief groove 300 and the duct 362 to the air intake 282 for the pump.

3 The system as disclosed in Fig. 5 in case the `oil supply becomes depleted requires no priming to reestablish operation, as the injector 220 acts as an air pump only and will create the necessary vacuum to pump when the fuel supply is replenished. The system is not adversely affected by air leaks in the line 228 other than a reduction in pumping capacity as the air entrained is released within the reservoirV 238 and is not reflected in a variation in theV combustion rate.` Also due to the fact that `the air does not have to be expelled from the system, it is sufcient to use only one pipe -to the supply tank, thereby eliminating the return line ordinarily employed on installations with a supply tank below the burner level.

While I have illustrated and described preferred embodiments of my invention, it is understood that these are capable -of modification and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. A fuel and air pumping arrangement for an oil burner for supplying air and oil to the nozzle thereof for mixture therein and discharge as a primary mixture therefrom, said arrangement comprising a reservoir for containing a body of oil and air under pressure, motor driven air pump means discharging into such reservoir so as to accumulate therein a mass of air under pressure above and in contact with the oil therein, said reservoir being provided with a fluid connection adapted for supplying oil from said reservoir to said nozzle in response to the pressure to which the oil in said reservoir is subjected by theair discharged by said air pump means, and a iluid connection adapted for supplying air under pressure from said reservoir to said nozzle, and means for supplying oil to said reservoir, said last mentioned means comprising an injector connected to said air pump means so as to be actuated by the air pumped thereby, an oil supply line, a transfer Vessel to which said oil supply line is connected, a communication between the top of said transfer vessel and the throat of said injector so as to reduce the pressure within said transfer `vessel during operation of said air pump, thereby to cause oil to flow through said supply line into said vessel to a level higher than that in said reservoir, pressure equalizing valve means between said transfer vessel and reservoir operable when the level of oil in said vessel attains a predetermined amount to establish communication and equalize the pressure therebetween, a flow control valve between said transfer vessel and reservoir operable upon equalization of pressure between said transfer vessel and reservoir to permit flow of oil from said transfer vessel to said reservoir, said pressure equalizing valve means and control valve being constructed and arranged to close upon equalization of the oil level in said reservoir and transfer vessel.

. 2. An arrangement according to claim l wherein said pressure equalizing valve means and control valve are of the normally closed type and each. includes a pressure responsive diaphragm exposed to the suction effect produced at the throat of said injector so as to be operated thereby, said pressure equalizing valve means and control valve incorporating provisions which cause said equalizing valve to operate before said ow control valve.

3. An arrangement according to claim l wherein a normally closed pressure responsive valve, arranged in said oil supply line, is provided with a pressure responsive element exposed to the interior of said vessel, said element being operable for effecting opening of said normally closed valve upon the reduction in pressure in said transfer vessel and to permit yclosing of said valve when said pressures in said vessel and reservoir are equalized.

4. A fuel and air pumping arrangement for an oil burner having an air and oil mixing nozzle to which air and oil are supplied for mixture therein and discharge as a primary mixture therefrom, said arrangement comprising a reservoir for containing a body of oil and air under pressure, motor driven air pump means discharging into such reservoir so as to accumulate therein a mass of air under pressure above and in contact with the oil therein, said reservoir being provided with a fluid connection adapted for supplying oil from said reservoir to said nozzle in response to the pressure to which the oil in said reservoir is subjected by the air discharged by said air pump means, and a lluid connection adapted for supplying air under pressure from said reservoir to said nozzle, and means for supplying oil to said reservoir, said last mentioned means comprising an injector connected to said air pump means so as to be actuated by the air pumped thereby, an oil supply line having a normally closed valve therein, a transfer vessel to which said oil supply line is connected, a communication between the top of said transfer vessel and the throat of said injector so as to reduce the pressure within said transfer vessel during operation of said air pump, thereby when said valve is open to induce oil to flow through said supply line into said vessel to a level higher than that in said reservoir, pressure equalizing valve means between said transfer vessel and reservoir operable when the level of oil in said vessel attains a predetermined amount to establish communication and equalize the pressure therebetween, means operable for opening said normally closed valve when the pressure in said transfer vessel is reduced and for closing said valve when the pressure in said transfer vessel and reservoir is equalized, a ow control valve betweeen said transfer vessel and reservoir operable upon`equalization of pressure between said transfer vessel and reservoir to permit flow of oil from said transfer vessel to said reservoir, said pressure equalizing valve means and control valve being constructed and arranged to close upon equalization of the oil level in said reservoir and transfer vessel.

5. An arrangement according to claim 4 wherein resistance means retard the ow of oil to said nozzle so as to permit the accumulation of air under pressure in said reservoir and wherein said reservoir is provided with pressure regulating means operable to maintain the air pressure therein during operation of said burner within predetermined limits so as to minimize fluctuations in the rate at which the oil and air mixture is discharged by said nozzle.

6. A fuel and air pumping arangement for an oil burner for supplying air and oil to the nozzle thereof for mixture therein and discharge therefrom as a primary mixture, said arrangement comprising a reservoir for containing a body of oil and air under pressure, motor driven air pump means discharging into such reservoir so as to accumulate therein a mass of air under pressure above and in contact with the oil therein, said reservoir being provided with a fluid connection adapted for supplying oil from said reservoir to said nozzle in response to the pressure to which the oil in said reservoir is subjccted by the air discharged by said air pump means, and a fluid connection adapted for supplying air under pressure to said nozzle from said reservoir, and means for supplying oil to said reservoir, said last mentioned means comprising an injector connected to said air pump means so as to be actuated by the air pumped thereby, an oil supply line, a transfer vessel to which said oil supply line is connected, a communication between said transfer vessel and the throat of said injector so as to reduce the pressure within said transfer vessel during operation of said air pump thereby to induce oil to flow through said supply line into said vessel to a level higher than that in said reservoir, and valve means associated with said transfer vessel and reservoir and oil supply line operable for controlling the flow of oil from said transfer vessel into said reservoir so as to maintain the oil in said reservoir within predetermined limits during operation of s aid air pump, and means for regulating the air pressure in said reservoir during operation of said burner within predetermined limits.

References Cited in the tile of this patent UNITED STATES PATENTS 1,537,687 Morris May 12, 1925 1,613,969 Swartz et al. Jan. 11, 1927 1,650,561 Williams Nov. 22, 1927 1,854,749 Lord Apr. 19, 1932 1,921,922 Herr Aug. 8, 1933 1,986,003 Lum Jan. 1, 1935 2,022,513 Macchi Nov. 26, 1935 2,516,063 Logan et al. July 18, 1950 

